Method and apparatus for improving one-to-one sidelink communication in a wireless communication system

ABSTRACT

A method and apparatus are disclosed from the perspective of a User Equipment (UE) for the UE to request sidelink resources for an one-to-one V2X (Vehicle-to-Everything) sidelink communication, wherein the UE supports both LTE (Long Term Evolution) RAT (Radio Access Technology) and NR (New Radio) RAT. In one embodiment, the method includes the UE initiating a one-to-one V2X sidelink communication. The method further includes the UE transmitting a RRC (Radio Resource Control) message to a network node to request sidelink resources from NR RAT for the one-to-one V2X sidelink communication and not transmitting any RRC message to the network node to request sidelink resources from LTE RAT for the one-to-one V2X sidelink communication.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present Application claims the benefit of U.S. Provisional PatentApplication Ser. No. 62/756,284 filed on Nov. 6, 2018, the entiredisclosure of which is incorporated herein in its entirety by reference.

FIELD

This disclosure generally relates to wireless communication networks,and more particularly, to a method and apparatus for improvingone-to-one sidelink communication in a wireless communication system.

BACKGROUND

With the rapid rise in demand for communication of large amounts of datato and from mobile communication devices, traditional mobile voicecommunication networks are evolving into networks that communicate withInternet Protocol (IP) data packets. Such IP data packet communicationcan provide users of mobile communication devices with voice over IP,multimedia, multicast and on-demand communication services.

An exemplary network structure is an Evolved Universal Terrestrial RadioAccess Network (E-UTRAN). The E-UTRAN system can provide high datathroughput in order to realize the above-noted voice over IP andmultimedia services. A new radio technology for the next generation(e.g., 5G) is currently being discussed by the 3GPP standardsorganization. Accordingly, changes to the current body of 3GPP standardare currently being submitted and considered to evolve and finalize the3GPP standard.

SUMMARY

A method and apparatus are disclosed from the perspective of a UserEquipment (UE) for the UE to request sidelink resources for anone-to-one V2X (Vehicle-to-Everything) sidelink communication, whereinthe UE supports both LTE (Long Term Evolution) RAT (Radio AccessTechnology) and NR (New Radio) RAT. In one embodiment, the methodincludes the UE initiating a one-to-one V2X sidelink communication. Themethod further includes the UE transmitting a RRC (Radio ResourceControl) message to a network node to request sidelink resources from NRRAT for the one-to-one V2X sidelink communication and not transmittingany RRC message to the network node to request sidelink resources fromLTE RAT for the one-to-one V2X sidelink communication.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a diagram of a wireless communication system according toone exemplary embodiment.

FIG. 2 is a block diagram of a transmitter system (also known as accessnetwork) and a receiver system (also known as user equipment or UE)according to one exemplary embodiment.

FIG. 3 is a functional block diagram of a communication system accordingto one exemplary embodiment.

FIG. 4 is a functional block diagram of the program code of FIG. 3according to one exemplary embodiment.

FIG. 5 is a reproduction of FIG. 6.1.3.1a-1 of 3GPP TS 36.321 V15.3.0.

FIG. 6 is a reproduction of FIG. 6.1.3.1a-2 of 3GPP TS 36.321 V15.3.0.

FIG. 7 is a reproduction of FIG. 6.1.6-1 of 3GPP TS 36.321 V15.3.0.

FIG. 8 is a reproduction of FIG. 6.1.6-2 of 3GPP TS 36.321 V15.3.0.

FIG. 9 is a reproduction of FIG. 6.1.6-3 of 3GPP TS 36.321 V15.3.0.

FIG. 10 is a reproduction of FIG. 6.1.6-3a of 3GPP TS 36.321 V15.3.0.

FIG. 11 is a reproduction of FIG. 6.1.6-4 of 3GPP TS 36.321 V15.3.0.

FIG. 12 is a reproduction of FIG. 5.10.2-1 of 3GPP TS 36.331 V15.2.2.

FIG. 13 is a diagram according to one exemplary embodiment.

FIG. 14 is a diagram according to one exemplary embodiment.

FIG. 15 is a diagram according to one exemplary embodiment.

FIG. 16 is a diagram according to one exemplary embodiment.

FIG. 17 is a flow chart according to one exemplary embodiment.

FIG. 18 is a flow chart according to one exemplary embodiment.

DETAILED DESCRIPTION

The exemplary wireless communication systems and devices described belowemploy a wireless communication system, supporting a broadcast service.Wireless communication systems are widely deployed to provide varioustypes of communication such as voice, data, and so on. These systems maybe based on code division multiple access (CDMA), time division multipleaccess (TDMA), orthogonal frequency division multiple access (OFDMA),3GPP LTE (Long Term Evolution) wireless access, 3GPP LTE-A orLTE-Advanced (Long Term Evolution Advanced), 3GPP2 UMB (Ultra MobileBroadband), WiMax, 3GPP NR (New Radio), or some other modulationtechniques.

In particular, the exemplary wireless communication systems devicesdescribed below may be designed to support one or more standards such asthe standard offered by a consortium named “3rd Generation PartnershipProject” referred to herein as 3GPP, including: TS 24.386 V15.1.0, “UserEquipment (UE) to V2X control function; protocol aspects; Stage 3(Release 15)”; TS 36.321 V15.3.0, “Evolved Universal Terrestrial RadioAccess (E-UTRA); Medium Access Control (MAC) protocol specification”;RAN1#94 Chairman's Note; TS 36.331 V15.2.2, “Evolved UniversalTerrestrial Radio Access (E-UTRA); Radio Resource Control (RRC);Protocol specification”. The standards and documents listed above arehereby expressly incorporated by reference in their entirety.

FIG. 1 shows a multiple access wireless communication system accordingto one embodiment of the invention. An access network 100 (AN) includesmultiple antenna groups, one including 104 and 106, another including108 and 110, and an additional including 112 and 114. In FIG. 1, onlytwo antennas are shown for each antenna group, however, more or fewerantennas may be utilized for each antenna group. Access terminal 116(AT) is in communication with antennas 112 and 114, where antennas 112and 114 transmit information to access terminal 116 over forward link120 and receive information from access terminal 116 over reverse link118. Access terminal (AT) 122 is in communication with antennas 106 and108, where antennas 106 and 108 transmit information to access terminal(AT) 122 over forward link 126 and receive information from accessterminal (AT) 122 over reverse link 124. In a FDD system, communicationlinks 118, 120, 124 and 126 may use different frequency forcommunication. For example, forward link 120 may use a differentfrequency then that used by reverse link 118.

Each group of antennas and/or the area in which they are designed tocommunicate is often referred to as a sector of the access network. Inthe embodiment, antenna groups each are designed to communicate toaccess terminals in a sector of the areas covered by access network 100.

In communication over forward links 120 and 126, the transmittingantennas of access network 100 may utilize beamforming in order toimprove the signal-to-noise ratio of forward links for the differentaccess terminals 116 and 122. Also, an access network using beamformingto transmit to access terminals scattered randomly through its coveragecauses less interference to access terminals in neighboring cells thanan access network transmitting through a single antenna to all itsaccess terminals.

An access network (AN) may be a fixed station or base station used forcommunicating with the terminals and may also be referred to as anaccess point, a Node B, a base station, an enhanced base station, anevolved Node B (eNB), or some other terminology. An access terminal (AT)may also be called user equipment (UE), a wireless communication device,terminal, access terminal or some other terminology.

FIG. 2 is a simplified block diagram of an embodiment of a transmittersystem 210 (also known as the access network) and a receiver system 250(also known as access terminal (AT) or user equipment (UE)) in a MIMOsystem 200. At the transmitter system 210, traffic data for a number ofdata streams is provided from a data source 212 to a transmit (TX) dataprocessor 214.

In one embodiment, each data stream is transmitted over a respectivetransmit antenna. TX data processor 214 formats, codes, and interleavesthe traffic data for each data stream based on a particular codingscheme selected for that data stream to provide coded data.

The coded data for each data stream may be multiplexed with pilot datausing OFDM techniques. The pilot data is typically a known data patternthat is processed in a known manner and may be used at the receiversystem to estimate the channel response. The multiplexed pilot and codeddata for each data stream is then modulated (i.e., symbol mapped) basedon a particular modulation scheme (e.g., BPSK, QPSK, M-PSK, or M-QAM)selected for that data stream to provide modulation symbols. The datarate, coding, and modulation for each data stream may be determined byinstructions performed by processor 230.

The modulation symbols for all data streams are then provided to a TXMIMO processor 220, which may further process the modulation symbols(e.g., for OFDM). TX MIMO processor 220 then provides N_(T) modulationsymbol streams to N_(T) transmitters (TMTR) 222 a through 222 t. Incertain embodiments, TX MIMO processor 220 applies beamforming weightsto the symbols of the data streams and to the antenna from which thesymbol is being transmitted.

Each transmitter 222 receives and processes a respective symbol streamto provide one or more analog signals, and further conditions (e.g.,amplifies, filters, and upconverts) the analog signals to provide amodulated signal suitable for transmission over the MIMO channel. N_(T)modulated signals from transmitters 222 a through 222 t are thentransmitted from N_(T) antennas 224 a through 224 t, respectively.

At receiver system 250, the transmitted modulated signals are receivedby N_(R) antennas 252 a through 252 r and the received signal from eachantenna 252 is provided to a respective receiver (RCVR) 254 a through254 r. Each receiver 254 conditions (e.g., filters, amplifies, anddownconverts) a respective received signal, digitizes the conditionedsignal to provide samples, and further processes the samples to providea corresponding “received” symbol stream.

An RX data processor 260 then receives and processes the N_(R) receivedsymbol streams from N_(R) receivers 254 based on a particular receiverprocessing technique to provide N_(T)“detected” symbol streams. The RXdata processor 260 then demodulates, deinterleaves, and decodes eachdetected symbol stream to recover the traffic data for the data stream.The processing by RX data processor 260 is complementary to thatperformed by TX MIMO processor 220 and TX data processor 214 attransmitter system 210.

A processor 270 periodically determines which pre-coding matrix to use(discussed below). Processor 270 formulates a reverse link messagecomprising a matrix index portion and a rank value portion.

The reverse link message may comprise various types of informationregarding the communication link and/or the received data stream. Thereverse link message is then processed by a TX data processor 238, whichalso receives traffic data for a number of data streams from a datasource 236, modulated by a modulator 280, conditioned by transmitters254 a through 254 r, and transmitted back to transmitter system 210.

At transmitter system 210, the modulated signals from receiver system250 are received by antennas 224, conditioned by receivers 222,demodulated by a demodulator 240, and processed by a RX data processor242 to extract the reserve link message transmitted by the receiversystem 250. Processor 230 then determines which pre-coding matrix to usefor determining the beamforming weights then processes the extractedmessage.

Turning to FIG. 3, this figure shows an alternative simplifiedfunctional block diagram of a communication device according to oneembodiment of the invention. As shown in FIG. 3, the communicationdevice 300 in a wireless communication system can be utilized forrealizing the UEs (or ATs) 116 and 122 in FIG. 1 or the base station (orAN) 100 in FIG. 1, and the wireless communications system is preferablythe LTE or NR system. The communication device 300 may include an inputdevice 302, an output device 304, a control circuit 306, a centralprocessing unit (CPU) 308, a memory 310, a program code 312, and atransceiver 314. The control circuit 306 executes the program code 312in the memory 310 through the CPU 308, thereby controlling an operationof the communications device 300. The communications device 300 canreceive signals input by a user through the input device 302, such as akeyboard or keypad, and can output images and sounds through the outputdevice 304, such as a monitor or speakers. The transceiver 314 is usedto receive and transmit wireless signals, delivering received signals tothe control circuit 306, and outputting signals generated by the controlcircuit 306 wirelessly. The communication device 300 in a wirelesscommunication system can also be utilized for realizing the AN 100 inFIG. 1.

FIG. 4 is a simplified block diagram of the program code 312 shown inFIG. 3 in accordance with one embodiment of the invention. In thisembodiment, the program code 312 includes an application layer 400, aLayer 3 portion 402, and a Layer 2 portion 404, and is coupled to aLayer 1 portion 406. The Layer 3 portion 402 generally performs radioresource control. The Layer 2 portion 404 generally performs linkcontrol. The Layer 1 portion 406 generally performs physicalconnections.

3GPP TS 24.386 V15.1.0 describes configuration parameters andtransmission behaviors related to transmission profile, destinationlayer-2 ID, and source layer-2 ID as follows:

5.2.4 Configuration Parameters for V2X Communication Over PC5

The configuration parameters for V2X communication over PC5 consist of:

-   -   a) an expiration time for the validity of the configuration        parameters for V2X communication over PC5;    -   b) a list of PLMNs in which the UE is authorized to use V2X        communication over PC5 when the UE is served by E-UTRAN for V2X        communication;    -   c) an indication of whether the UE is authorized to use V2X        communication over PC5 when the UE is not served by E-UTRAN for        V2X communication;    -   d) per geographical area:        -   1) radio parameters for V2X communication over PC5            applicable when the UE is not served by E-UTRAN for V2X            communication and is located in the geographical area, with            an indication of whether these radio parameters are            “operator managed” or “non-operator managed”;    -   e) a list of the V2X services authorized for V2X communication        over PC5. Each entry of the list contains:

1) a V2X service identifier; and

2) a destination Layer-2 ID;

-   -   f) PPPP to PDB mapping rules between the ProSe Per-Packet        Priority (PPPP) and the Packet Delay Budget (PDB) for V2X        communication over PC5;    -   g) optionally, a default destination Layer-2 ID;    -   h) optionally, a configuration for the applicability of privacy        for V2X communication over PC5, containing:        -   1) a T5000 timer indicating how often the UE shall change            the source Layer-2 ID and source IP address (for IP data)            self-assigned by the UE for V2X communication over PC5; and        -   2) a list of the V2X services which require privacy for V2X            communication over PC5. Each entry in the list contains:            -   A) a V2X service identifier; and            -   B) optionally, one or more associated geographical                areas;    -   i) optionally, V2X service identifier to V2X frequency mapping        rules between the V2X service identifiers and the V2X        frequencies with associated geographical areas for V2X        communication over PC5; and    -   j) optionally, a list of the V2X services authorized for ProSe        Per-Packet Reliability (PPPR). Each entry of the list contains a        V2X service identifier and a ProSe Per-Packet Reliability (PPPR)        value; and    -   k) optionally, V2X service identifier to Tx Profile mapping        rules between the V2X service identifiers and the Tx Profile for        V2X communication over PC5.        [ . . . ]        6.1.2.2 Transmission

The UE shall include the V2X message in a protocol data unit and pass itto the lower layers for transmission along with the followingparameters:

-   -   a) a Layer-3 protocol data unit type (see 3GPP TS 36.323 [8])        set to:        -   1) IP packet, if the V2X message contains IP data; or        -   2) non-IP packet, if the V2X message contains non-IP data;    -   b) the source Layer-2 ID set to the Layer-2 ID self-assigned by        the UE for V2X communication over PC5;    -   c) the destination Layer-2 ID set to:        -   1) the destination Layer-2 ID associated with the V2X            service identifier of the V2X service in this list of V2X            services authorized for V2X communication over PC5 as            specified in subclause 5.2.4, if the V2X service identifier            of the V2X service is included in the list of V2X services            authorized for V2X communication over PC5 as specified in            subclause 5.2.4; or        -   2) the default destination Layer-2 ID configured to the UE            for V2X communication over PC5 as specified in subclause            5.2.4, if the V2X service identifier of the V2X service is            not included in the list of V2X services authorized for V2X            communication over PC5 and the UE is configured with a            default destination Layer-2 ID for V2X communication over            PC5;    -   d) if the V2X message contains non-IP data, an indication to set        the non-IP type field of the non-IP type PDU to the value        corresponding to the V2X message family (see subclause 7.1) used        by the V2X service as indicated by upper layers;    -   e) if the V2X message contains IP data, the source IP address        set to the source IP address self-assigned by the UE for V2X        communication over PC5;    -   f) the ProSe Per-Packet Priority set to the value corresponding        to the V2X message priority received from upper layers. The        mapping of V2X message priority to ProSe Per-Packet Priority is        configured on the UE and is out of the scope of this        specification;    -   g) if the UE is configured with PDB (Packet Delay        Budget)-to-ProSe Per-Packet Priority mapping rules for V2X        communication over PC5 as specified in subclause 5.2.4, the PDB        associated with the ProSe Per-Packet Priority as specified in        subclause 5.2.4;    -   h) if:        -   1) a ProSe Per-Packet Reliability (PPPR) value is received            from the upper layers; and        -   2) one of the following conditions is met:            -   A) the list of the V2X services authorized for ProSe                Per-Packet Reliability (PPPR) is not configured; or            -   B) the V2X service identifier of the V2X service for the                V2X message and the received ProSe Per-Packet                Reliability (PPPR) value are included in an entry of the                list of the V2X services authorized for ProSe Per-Packet                Reliability (PPPR);

then the ProSe Per-Packet Reliability (PPPR) value; and

-   -   i) if the UE is configured with V2X service identifier to Tx        Profile mapping rules for V2X communication over PC5 as        specified in subclause 5.2.4, the Tx Profile associated with the        V2X service identifier as specified in subclause 5.2.4.        If the UE has an emergency PDN connection, the UE shall send an        indication to the lower layers to prioritize transmission over        the emergency PDN connection as compared to transmission of V2X        communication over PC5.

Sidelink resource allocation and utilization mechanism are described inthe current MAC specification (3GPP TS 36.321 V15.3.0) as follows:

5.14 SL-SCH Data Transfer

5.14.1 SL-SCH Data Transmission

5.14.1.1 SL Grant Reception and SCI Transmission

In order to transmit on the SL-SCH the MAC entity must have at least onesidelink grant.

Sidelink grants are selected as follows for sidelink communication:

-   -   if the MAC entity is configured to receive a single sidelink        grant dynamically on the PDCCH and more data is available in        STCH than can be transmitted in the current SC period, the MAC        entity shall:        -   using the received sidelink grant determine the set of            subframes in which transmission of SCI and transmission of            first transport block occur according to subclause 14.2.1 of            [2];        -   consider the received sidelink grant to be a configured            sidelink grant occurring in those subframes starting at the            beginning of the first available SC Period which starts at            least 4 subframes after the subframe in which the sidelink            grant was received, overwriting a previously configured            sidelink grant occurring in the same SC period, if            available;        -   clear the configured sidelink grant at the end of the            corresponding SC Period;    -   else, if the MAC entity is configured by upper layers to receive        multiple sidelink grants dynamically on the PDCCH and more data        is available in STCH than can be transmitted in the current SC        period, the MAC entity shall for each received sidelink grant:        -   using the received sidelink grant determine the set of            subframes in which transmission of SCI and transmission of            first transport block occur according to subclause 14.2.1 of            [2];        -   consider the received sidelink grant to be a configured            sidelink grant occurring in those subframes starting at the            beginning of the first available SC Period which starts at            least 4 subframes after the subframe in which the sidelink            grant was received, overwriting a previously configured            sidelink grant received in the same subframe number but in a            different radio frame as this configured sidelink grant            occurring in the same SC period, if available;        -   clear the configured sidelink grant at the end of the            corresponding SC Period;    -   else, if the MAC entity is configured by upper layers to        transmit using one or multiple pool(s) of resources as indicated        in subclause 5.10.4 of [8] and more data is available in STCH        than can be transmitted in the current SC period, the MAC entity        shall for each sidelink grant to be selected:        -   if configured by upper layers to use a single pool of            resources:            -   select that pool of resources for use;        -   else, if configured by upper layers to use multiple pools of            resources:            -   select a pool of resources for use from the pools of                resources configured by upper layers whose associated                priority list includes the priority of the highest                priority of the sidelink logical channel in the MAC PDU                to be transmitted;            -   NOTE: If more than one pool of resources has an                associated priority list which includes the priority of                the sidelink logical channel with the highest priority                in the MAC PDU to be transmitted, it is left for UE                implementation which one of those pools of resources to                select.        -   randomly select the time and frequency resources for SL-SCH            and SCI of a sidelink grant from the selected resource pool.            The random function shall be such that each of the allowed            selections [2] can be chosen with equal probability;        -   use the selected sidelink grant to determine the set of            subframes in which transmission of SCI and transmission of            first transport block occur according to subclause 14.2.1 of            [2];        -   consider the selected sidelink grant to be a configured            sidelink grant occurring in those subframes starting at the            beginning of the first available SC Period which starts at            least 4 subframes after the subframe in which the sidelink            grant was selected;        -   clear the configured sidelink grant at the end of the            corresponding SC Period;            -   NOTE: Retransmissions on SL-SCH cannot occur after the                configured sidelink grant has been cleared.            -   NOTE: If the MAC entity is configured by upper layers to                transmit using one or multiple pool(s) of resources as                indicated in subclause 5.10.4 of [8], it is left for UE                implementation how many sidelink grants to select within                one SC period taking the number of sidelink processes                into account.                Sidelink grants are selected as follows for V2X sidelink                communication:    -   if the MAC entity is configured to receive a sidelink grant        dynamically on the PDCCH and data is available in STCH, the MAC        entity shall:        -   use the received sidelink grant to determine the number of            HARQ retransmissions and the set of subframes in which            transmission of SCI and SL-SCH occur according to subclause            14.2.1 and 14.1.1.4A of [2];        -   consider the received sidelink grant to be a configured            sidelink grant;    -   if the MAC entity is configured by upper layers to receive a        sidelink grant on the PDCCH addressed to SL Semi-Persistent        Scheduling V-RNTI, the MAC entity shall for each SL SPS        configuration:        -   if PDCCH contents indicate SPS activation:            -   use the received sidelink grant to determine the number                of HARQ retransmissions and the set of subframes in                which transmission of SCI and SL-SCH occur according to                subclause 14.2.1 and 14.1.1.4A of [2];            -   consider the received sidelink grant to be a configured                sidelink grant;        -   if PDCCH contents indicate SPS release:            -   clear the corresponding configured sidelink grant;    -   if the MAC entity is configured by upper layers to transmit        using pool(s) of resources in one or multiple carriers as        indicated in subclause 5.10.13.1 of [8] based on sensing, or        partial sensing, or random selection only if upper layers        indicates that transmissions of multiple MAC PDUs are allowed        according to subclause 5.10.13.1a of [8], and the MAC entity        selects to create a configured sidelink grant corresponding to        transmissions of multiple MAC PDUs, and data is available in        STCH associated with one or multiple carriers, the MAC entity        shall for each Sidelink process configured for multiple        transmissions on a selected carrier according to subclause        5.14.1.5:        -   if SL_RESOURCE_RESELECTION_COUNTER=0 and when            SL_RESOURCE_RESELECTION_COUNTER was equal to 1 the MAC            entity randomly selected, with equal probability, a value in            the interval [0, 1] which is above the probability            configured by upper layers in probResourceKeep; or        -   if neither transmission nor retransmission has been            performed by the MAC entity on any resource indicated in the            configured sidelink grant during the last second; or        -   if sl-ReselectAfter is configured and the number of            consecutive unused transmission opportunities on resources            indicated in the configured sidelink grant is equal to            sl-ReselectAfter; or        -   if there is no configured sidelink grant; or        -   if the configured sidelink grant cannot accommodate a RLC            SDU by using the maximum allowed MCS configured by upper            layers in maxMCS-PSSCH and the MAC entity selects not to            segment the RLC SDU; or            -   NOTE: If the configured sidelink grant cannot                accommodate the RLC SDU, it is left for UE                implementation whether to perform segmentation or                sidelink resource reselection.        -   if transmission(s) with the configured sidelink grant cannot            fulfil the latency requirement of the data in a sidelink            logical channel according to the associated PPPP, and the            MAC entity selects not to perform transmission(s)            corresponding to a single MAC PDU; or            -   NOTE: If the latency requirement is not met, it is left                for UE implementation whether to perform transmission(s)                corresponding to single MAC PDU or sidelink resource                reselection.        -   if a pool of resources is configured or reconfigured by            upper layers for the selected carrier:            -   clear the configured sidelink grant, if available;            -   trigger the TX carrier (re-)selection procedure as                specified in sub-clause 5.14.1.5;        -   if the carrier is (re-)selected in the Tx carrier            (re-)selection according to sub-clause 5.14.1.5, the            following is performed on the selected carrier:            -   select one of the allowed values configured by upper                layers in restrictResourceReservationPeriod and set the                resource reservation interval by multiplying 100 with                the selected value;            -   NOTE: How the UE selects this value is up to UE                implementation.            -   randomly select, with equal probability, an integer                value in the interval [5, 15] for the resource                reservation interval higher than or equal to 100 ms, in                the interval [10, 30] for the resource reservation                interval equal to 50 ms or in the interval [25, 75] for                the resource reservation interval equal to 20 ms, and                set SL_RESOURCE_RESELECTION_COUNTER to the selected                value;            -   select the number of HARQ retransmissions from the                allowed numbers that are configured by upper layers in                allowedRetxNumberPSSCH included in pssch-TxConfigList                and, if configured by upper layers, overlapped in                allowedRetxNumberPSSCH indicated in                cbr-pssch-TxConfigList for the highest priority of the                sidelink logical channel(s) allowed on the selected                carrier and the CBR measured by lower layers according                to [6] if CBR measurement results are available or the                corresponding defaultTxConfigIndex configured by upper                layers if CBR measurement results are not available;            -   select an amount of frequency resources within the range                that is configured by upper layers between                minSubchannel-NumberPSSCH and maxSubchannel-NumberPSSCH                included in pssch-TxConfigList and, if configured by                upper layers, overlapped between                minSubchannel-NumberPSSCH and maxSubchannel-NumberPSSCH                indicated in cbr-pssch-TxConfigList for the highest                priority of the sidelink logical channel(s) allowed on                the selected carrier and the CBR measured by lower                layers according to [6] if CBR measurement results are                available or the corresponding defaultTxConfigIndex                configured by upper layers if CBR measurement results                are not available;            -   if transmission based on random selection is configured                by upper layers:            -   randomly select the time and frequency resources for one                transmission opportunity from the resource pool,                according to the amount of selected frequency resources.                The random function shall be such that each of the                allowed selections can be chosen with equal probability;            -   else:            -   randomly select the time and frequency resources for one                transmission opportunity from the resources indicated by                the physical layer according to subclause 14.1.1.6 of                [2], according to the amount of selected frequency                resources. The random function shall be such that each                of the allowed selections can be chosen with equal                probability;            -   use the randomly selected resource to select a set of                periodic resources spaced by the resource reservation                interval for transmission opportunities of SCI and                SL-SCH corresponding to the number of transmission                opportunities of MAC PDUs determined in subclause                14.1.1.4B of [2];            -   if the number of HARQ retransmissions is equal to 1 and                there are available resources left in the resources                indicated by the physical layer that meet the conditions                in subclause 14.1.1.7 of [2] for more transmission                opportunities:            -   randomly select the time and frequency resources for one                transmission opportunity from the available resources,                according to the amount of selected frequency resources.                The random function shall be such that each of the                allowed selections can be chosen with equal probability;            -   use the randomly selected resource to select a set of                periodic resources spaced by the resource reservation                interval for the other transmission opportunities of SCI                and SL-SCH corresponding to the number of retransmission                opportunities of the MAC PDUs determined in subclause                14.1.1.4B of [2];            -   consider the first set of transmission opportunities as                the new transmission opportunities and the other set of                transmission opportunities as the retransmission                opportunities;            -   consider the set of new transmission opportunities and                retransmission opportunities as the selected sidelink                grant.            -   else:            -   consider the set as the selected sidelink grant;            -   use the selected sidelink grant to determine the set of                subframes in which transmissions of SCI and SL-SCH occur                according to subclause 14.2.1 and 14.1.1.4B of [2];            -   consider the selected sidelink grant to be a configured                sidelink grant;        -   else if SL_RESOURCE_RESELECTION_COUNTER=0 and when            SL_RESOURCE_RESELECTION_COUNTER was equal to 1 the MAC            entity randomly selected, with equal probability, a value in            the interval [0, 1] which is less than or equal to the            probability configured by upper layers in probResourceKeep:            -   clear the configured sidelink grant, if available;            -   randomly select, with equal probability, an integer                value in the interval [5, 15] for the resource                reservation interval higher than or equal to 100 ms, in                the interval [10, 30] for the resource reservation                interval equal to 50 ms or in the interval [25, 75] for                the resource reservation interval equal to 20 ms, and                set SL_RESOURCE_RESELECTION_COUNTER to the selected                value;            -   use the previously selected sidelink grant for the                number of transmissions of the MAC PDUs determined in                subclause 14.1.1.4B of [2] with the resource reservation                interval to determine the set of subframes in which                transmissions of SCI and SL-SCH occur according to                subclause 14.2.1 and 14.1.1.4B of [2];            -   consider the selected sidelink grant to be a configured                sidelink grant;    -   else, if the MAC entity is configured by upper layers to        transmit using pool(s) of resources in one or multiple carriers        as indicated in subclause 5.10.13.1 of [8], the MAC entity        selects to create a configured sidelink grant corresponding to        transmission(s) of a single MAC PDU, and data is available in        STCH associated with one or multiple carriers, the MAC entity        shall for a Sidelink process on a selected carrier according to        subclause 5.14.1.5:        -   trigger the TX carrier (re-)selection procedure as specified            in sub-clause 5.14.1.5;        -   if the carrier is (re-)selected in the Tx carrier            (re-)selection according to sub-clause 5.14.1.5, the            following is performed on the selected carrier:            -   select the number of HARQ retransmissions from the                allowed numbers that are configured by upper layers in                allowedRetxNumberPSSCH included in pssch-TxConfigList                and, if configured by upper layers, overlapped in                allowedRetxNumberPSSCH indicated in                cbr-pssch-TxConfigList for the highest priority of the                sidelink logical channel(s) allowed on the selected                carrier and the CBR measured by lower layers according                to [6] if CBR measurement results are available or the                corresponding defaultTxConfigIndex configured by upper                layers if CBR measurement results are not available;            -   select an amount of frequency resources within the range                that is configured by upper layers between                minSubchannel-NumberPSSCH and maxSubchannel-NumberPSSCH                included in pssch-TxConfigList and, if configured by                upper layers, overlapped between                minSubchannel-NumberPSSCH and maxSubchannel-NumberPSSCH                indicated in cbr-pssch-TxConfigList for the highest                priority of the sidelink logical channel(s) allowed on                the selected carrier and the CBR measured by lower                layers according to [6] if CBR measurement results are                available or the corresponding defaultTxConfigIndex                configured by upper layers if CBR measurement results                are not available;            -   if transmission based on random selection is configured                by upper layers:            -   randomly select the time and frequency resources for one                transmission opportunity of SCI and SL-SCH from the                resource pool, according to the amount of selected                frequency resources. The random function shall be such                that each of the allowed selections can be chosen with                equal probability;            -   else:            -   randomly select the time and frequency resources for one                transmission opportunity of SCI and SL-SCH from the                resources indicated by the physical layer according to                subclause 14.1.1.6 of [2], according to the amount of                selected frequency resources. The random function shall                be such that each of the allowed selections can be                chosen with equal probability;            -   if the number of HARQ retransmissions is equal to 1:            -   if transmission based on random selection is configured                by upper layers and there are available resources that                meet the conditions in subclause 14.1.1.7 of [2] for one                more transmission opportunity:                -   randomly select the time and frequency resources for                    the other transmission opportunity of SCI and SL-SCH                    corresponding to additional transmission of the MAC                    PDU from the available resources, according to the                    amount of selected frequency resources. The random                    function shall be such that each of the allowed                    selections can be chosen with equal probability;            -   else, if transmission based on sensing or partial                sensing is configured by upper layers and there are                available resources left in the resources indicated by                the physical layer that meet the conditions in subclause                14.1.1.7 of [2] for one more transmission opportunity:                -   randomly select the time and frequency resources for                    the other transmission opportunity of SCI and SL-SCH                    corresponding to additional transmission of the MAC                    PDU from the available resources, according to the                    amount of selected frequency resources. The random                    function shall be such that each of the allowed                    selections can be chosen with equal probability;            -   consider a transmission opportunity which comes first in                time as the new transmission opportunity and a                transmission opportunity which comes later in time as                the retransmission opportunity;            -   consider both of the transmission opportunities as the                selected sidelink grant;            -   else:            -   consider the transmission opportunity as the selected                sidelink grant;            -   use the selected sidelink grant to determine the                subframes in which transmission(s) of SCI and SL-SCH                occur according to subclause 14.2.1 and 14.1.1.4B of                [2];            -   consider the selected sidelink grant to be a configured                sidelink grant.            -   NOTE: For V2X sidelink communication, the UE should                ensure the randomly selected time and frequency                resources fulfill the latency requirement.            -   NOTE: For V2X sidelink communication, when there is no                overlapping between the chosen configuration(s) in                pssch-TxConfigList and chosen configuration(s) indicated                in cbr-pssch-TxConfigList, it is up to UE implementation                whether the UE transmits and which transmitting                parameters the UE uses between allowed configuration(s)                indicated in pssch-TxConfigList and allowed                configuration(s) indicated in cbr-pssch-TxConfigList.                The MAC entity shall for each subframe:    -   if the MAC entity has a configured sidelink grant occurring in        this subframe:        -   if SL_RESOURCE_RESELECTION_COUNTER=1 and the MAC entity            randomly selected, with equal probability, a value in the            interval [0, 1] which is above the probability configured by            upper layers in probResourceKeep:            -   set the resource reservation interval equal to 0;        -   if the configured sidelink grant corresponds to transmission            of SCI:            -   for V2X sidelink communication in UE autonomous resource                selection:            -   select a MCS which is, if configured, within the range                that is configured by upper layers between minMCS-PSSCH                and maxMCS-PSSCH included in pssch-TxConfigList and, if                configured by upper layers, overlapped between                minMCS-PSSCH and maxMCS-PSSCH indicated in                cbr-pssch-TxConfigList for the highest priority of the                sidelink logical channel(s) in the MAC PDU and the CBR                measured by lower layers according to [6] if CBR                measurement results are available or the corresponding                defaultTxConfigIndex configured by upper layers if CBR                measurement results are not available;                -   NOTE: MCS selection is up to UE implementation if                    the MCS or the corresponding range is not configured                    by upper layers.                -   NOTE: For V2X sidelink communication, when there is                    no overlapping between the chosen configuration(s)                    included in pssch-TxConfigList and chosen                    configuration(s) indicated in                    cbr-pssch-TxConfigList, it is up to UE                    implementation whether the UE transmits and which                    transmitting parameters the UE uses between allowed                    configuration(s) indicated in pssch-TxConfigList and                    allowed configuration(s) indicated in                    cbr-pssch-TxConfigList.            -   for V2X sidelink communication in scheduled resource                allocation:            -   select a MCS unless it is configured by upper layer;            -   instruct the physical layer to transmit SCI                corresponding to the configured sidelink grant;            -   for V2X sidelink communication, deliver the configured                sidelink grant, the associated HARQ information and the                value of the highest priority of the sidelink logical                channel(s) in the MAC PDU to the Sidelink HARQ Entity                for this subframe;        -   else if the configured sidelink grant corresponds to            transmission of first transport block for sidelink            communication:            -   deliver the configured sidelink grant and the associated                HARQ information to the Sidelink HARQ Entity for this                subframe.            -   NOTE: If the MAC entity has multiple configured grants                occurring in one subframe and if not all of them can be                processed due to the single-cluster SC-FDM restriction,                it is left for UE implementation which one of these to                process according to the procedure above.                5.14.1.4 Buffer Status Reporting                The sidelink Buffer Status reporting procedure is used                to provide the serving eNB with information about the                amount of sidelink data available for transmission in                the SL buffers associated with the MAC entity. RRC                controls BSR reporting for the sidelink by configuring                the two timers periodic-BSR-TimerSL and                retx-BSR-TimerSL. Each sidelink logical channel belongs                to a ProSe Destination. Each sidelink logical channel is                allocated to an LCG depending on the priority and                optionally the PPPR of the sidelink logical channel, and                the mapping between LCG ID and priority and optionally                the mapping between LCG ID and PPPR which are provided                by upper layers in logicalChGroupInfoList [8]. LCG is                defined per ProSe Destination.                A sidelink Buffer Status Report (BSR) shall be triggered                if any of the following events occur:    -   if the MAC entity has a configured SL-RNTI or a configured        SL-V-RNTI:        -   SL data, for a sidelink logical channel of a ProSe            Destination, becomes available for transmission in the RLC            entity or in the PDCP entity (the definition of what data            shall be considered as available for transmission is            specified in [3] and [4] respectively) and either the data            belongs to a sidelink logical channel with higher priority            than the priorities of the sidelink logical channels which            belong to any LCG belonging to the same ProSe Destination            and for which data is already available for transmission, or            there is currently no data available for transmission for            any of the sidelink logical channels belonging to the same            ProSe Destination, in which case the Sidelink BSR is            referred below to as “Regular Sidelink BSR”;        -   UL resources are allocated and number of padding bits            remaining after a Padding BSR has been triggered is equal to            or larger than the size of the Sidelink BSR MAC control            element containing the buffer status for at least one LCG of            a ProSe Destination plus its subheader, in which case the            Sidelink BSR is referred below to as “Padding Sidelink BSR”;        -   retx-BSR-TimerSL expires and the MAC entity has data            available for transmission for any of the sidelink logical            channels, in which case the Sidelink BSR is referred below            to as “Regular Sidelink BSR”;        -   periodic-BSR-TimerSL expires, in which case the Sidelink BSR            is referred below to as “Periodic Sidelink BSR”;    -   else:        -   An SL-RNTI or an SL-V-RNTI is configured by upper layers and            SL data is available for transmission in the RLC entity or            in the PDCP entity (the definition of what data shall be            considered as available for transmission is specified in [3]            and [4] respectively), in which case the Sidelink BSR is            referred below to as “Regular Sidelink BSR”.            For Regular and Periodic Sidelink BSR:    -   if the number of bits in the UL grant is equal to or larger than        the size of a Sidelink BSR containing buffer status for all LCGs        having data available for transmission plus its subheader:        -   report Sidelink BSR containing buffer status for all LCGs            having data available for transmission;    -   else report Truncated Sidelink BSR containing buffer status for        as many LCGs having data available for transmission as possible,        taking the number of bits in the UL grant into consideration.        For Padding Sidelink BSR:    -   if the number of padding bits remaining after a Padding BSR has        been triggered is equal to or larger than the size of a Sidelink        BSR containing buffer status for all LCGs having data available        for transmission plus its subheader:        -   report Sidelink BSR containing buffer status for all LCGs            having data available for transmission;    -   else report Truncated Sidelink BSR containing buffer status for        as many LCGs having data available for transmission as possible,        taking the number of bits in the UL grant into consideration.        If the Buffer Status reporting procedure determines that at        least one Sidelink BSR has been triggered and not cancelled:    -   if the MAC entity has UL resources allocated for new        transmission for this TTI and the allocated UL resources can        accommodate a Sidelink BSR MAC control element plus its        subheader as a result of logical channel prioritization:        -   instruct the Multiplexing and Assembly procedure to generate            the Sidelink BSR MAC control element(s);        -   start or restart periodic-BSR-TimerSL except when all the            generated Sidelink BSRs are Truncated Sidelink BSRs;        -   start or restart retx-BSR-TimerSL;    -   else if a Regular Sidelink BSR has been triggered:        -   if an uplink grant is not configured:            -   a Scheduling Request shall be triggered.                A MAC PDU shall contain at most one Sidelink BSR MAC                control element, even when multiple events trigger a                Sidelink BSR by the time a Sidelink BSR can be                transmitted in which case the Regular Sidelink BSR and                the Periodic Sidelink BSR shall have precedence over the                padding Sidelink BSR.                The MAC entity shall restart retx-BSR-TimerSL upon                reception of an SL grant.                All triggered regular Sidelink BSRs shall be cancelled                in case the remaining configured SL grant(s) valid for                this SC Period can accommodate all pending data                available for transmission in sidelink communication or                in case the remaining configured SL grant(s) valid can                accommodate all pending data available for transmission                in V2X sidelink communication. All triggered Sidelink                BSRs shall be cancelled in case the MAC entity has no                data available for transmission for any of the sidelink                logical channels. All triggered Sidelink BSRs shall be                cancelled when a Sidelink BSR (except for Truncated                Sidelink BSR) is included in a MAC PDU for transmission.                All triggered Sidelink BSRs shall be cancelled, and                retx-BSR-TimerSL and periodic-BSR-TimerSL shall be                stopped, when upper layers configure autonomous resource                selection.                The MAC entity shall transmit at most one                Regular/Periodic Sidelink BSR in a TTI. If the MAC                entity is requested to transmit multiple MAC PDUs in a                TTI, it may include a padding Sidelink BSR in any of the                MAC PDUs which do not contain a Regular/Periodic                Sidelink BSR.                All Sidelink BSRs transmitted in a TTI always reflect                the buffer status after all MAC PDUs have been built for                this TTI. Each LCG shall report at the most one buffer                status value per TTI and this value shall be reported in                all Sidelink BSRs reporting buffer status for this LCG.    -   NOTE: A Padding Sidelink BSR is not allowed to cancel a        triggered Regular/Periodic Sidelink BSR. A Padding Sidelink BSR        is triggered for a specific MAC PDU only and the trigger is        cancelled when this MAC PDU has been built.        5.14.1.5 TX Carrier (Re-)Selection for V2X Sidelink        Communication        The MAC entity shall consider a CBR of a carrier to be one        measured by lower layers according to 3GPP TS 36.214 [6] if CBR        measurement results are available, or the corresponding        defaultTxConfigIndex configured by upper layers for the carrier        if CBR measurement results are not available.        The MAC entity shall:    -   if the MAC entity is configured by upper layers to transmit        using pool(s) of resources on one or multiple carriers as        indicated in subclause 5.10.13.1 of 3GPP TS 36.331 [8] and data        is available in STCH (i.e. initial Tx carrier selection):        -   for each sidelink logical channel where data is available:            -   for each carrier configured by upper layers (3GPP TS                24.386 [15]) associated with the concerned sidelink                logical channel:            -   if the CBR of the carrier is below                threshCBR-FreqReselection associated with the priority                of the sidelink logical channel:                -   consider the carrier as a candidate carrier for TX                    carrier (re-)selection for the concerned sidelink                    logical channel.    -   else if the MAC entity has been configured by upper layers to        transmit using pool(s) of resources on one or multiple carriers        as indicated in subclause 5.10.13.1 of 3GPP TS 36.331 [8], and        the TX carrier reselection is triggered for a process associated        with a carrier according to sub-clause 5.14.1.1 (i.e. Tx carrier        reselection):        -   for each sidelink logical channel allowed on the carrier            where data is available and Tx carrier (re-)selection is            triggered:            -   if the CBR of the carrier is below threshCBR-FreqKeeping                associated with priority of sidelink logical channel:            -   select the carrier and the associated pool of resources.            -   else:            -   for each carrier configured by upper layers, if the CBR                of the carrier is below threshCBR-FreqReselection                associated with the priority of the sidelink logical                channel;            -   consider the carrier as a candidate carrier for TX                carrier (re-)selection.                The MAC entity shall:    -   if one or more carriers are considered as the candidate carriers        for TX carrier (re-)selection:        -   for each sidelink logical channel allowed on the carrier            where data is available and Tx carrier (re-)selection is            triggered, select one or more carrier(s) and associated            pool(s) of resources among the candidate carriers with            increasing order of CBR from the lowest CBR;            -   NOTE 1: It is left to UE implementation how many                carriers to select based on UE capability.            -   NOTE 2: It is left to UE implementation to determine the                sidelink logical channels for which Tx carrier (re-)                selection is triggered among the sidelink logical                channels allowed on the carrier.            -   NOTE 3: If the MAC entity is configured by the upper                layer to receive a sidelink grant dynamically on the                PDCCH, it is left to UE implementation to determine                which carriers configured by upper layer in                sl-V2X-ConfigDedicated [8] are considered as selected                carriers.                6.1.3.1a Sidelink BSR MAC Control Elements                Sidelink BSR and Truncated Sidelink BSR MAC control                elements consist of one Destination Index field, one LCG                ID field and one corresponding Buffer Size field per                reported target group.                The Sidelink BSR MAC control elements are identified by                MAC PDU subheaders with LCIDs as specified in table                6.2.1-2. They have variable sizes.                For each included group, the fields are defined as                follows (FIGS. 6.1.3.1a-1 and 6.1.3.1a-2):    -   Destination Index: The Destination Index field identifies the        ProSe Destination or the destination for V2X sidelink        communication. The length of this field is 4 bits. The value is        set to the index of the destination reported in        destinationInfoList for sidelink communication or is set to one        index among index(es) associated to same destination reported in        v2x-DestinationInfoList for V2X sidelink communication. If        multiple such lists are reported, the value is indexed        sequentially across all the lists in the same order as specified        in [8];    -   LCG ID: The Logical Channel Group ID field identifies the group        of logical channel(s) which buffer status is being reported. The        length of the field is 2 bits;    -   Buffer Size: The Buffer Size field identifies the total amount        of data available across all logical channels of a LCG of a        ProSe Destination after all MAC PDUs for the TTI have been        built. The amount of data is indicated in number of bytes. It        shall include all data that is available for transmission in the        RLC layer and in the PDCP layer; the definition of what data        shall be considered as available for transmission is specified        in [3] and [4] respectively. The size of the RLC and MAC headers        are not considered in the buffer size computation. The length of        this field is 6 bits. The values taken by the Buffer Size field        are shown in Table 6.1.3.1-1;    -   R: Reserved bit, set to “0”.        Buffer Sizes of LCGs are included in decreasing order of the        highest priority of the sidelink logical channel belonging to        the LCG irrespective of the value of the Destination Index        field.    -   [FIG. 6.1.3.1a-1 of 3GPP TS 36.321 V15.3.0, entitled “Sidelink        BSR and Truncated Sidelink BSR MAC control element for even N”,        is reproduced as FIG. 5]    -   [FIG. 6.1.3.1a-2 of 3GPP TS 36.321 V15.3.0, entitled “Sidelink        BSR and Truncated Sidelink BSR MAC control element for odd N”,        is reproduced as FIG. 6]        [ . . . ]        6.1.6 MAC PDU (SL-SCH)        A MAC PDU consists of a MAC header, one or more MAC Service Data        Units (MAC SDU), and optionally padding; as described in FIG.        6.1.6-4.        Both the MAC header and the MAC SDUs are of variable sizes.        A MAC PDU header consists of one SL-SCH subheader, one or more        MAC PDU subheaders; each subheader except SL-SCH subheader        corresponds to either a MAC SDU or padding.        The SL-SCH subheader consists of the seven header fields        V/R/R/R/R/SRC/DST.        A MAC PDU subheader consists of the six header fields        R/R/E/LCID/F/L but for the last subheader in the MAC PDU. The        last subheader in the MAC PDU consists solely of the four header        fields R/R/E/LCID. A MAC PDU subheader corresponding to padding        consists of the four header fields R/R/E/LCID.    -   [FIG. 6.1.6-1 of 3GPP TS 36.321 V15.3.0, entitled        “R/R/E/LCID/F/L MAC subheader”, is reproduced as FIG. 7]    -   [FIG. 6.1.6-2 of 3GPP TS 36.321 V15.3.0, entitled “R/R/E/LCID        MAC SUBHEADER”, is reproduced as FIG. 8]    -   [FIG. 6.1.6-3 of 3GPP TS 36.321 V15.3.0, entitled “SL-SCH MAC        subheader for V=‘0001’ and ‘0010’”, is reproduced as FIG. 9]    -   [FIG. 6.1.6-3a of 3GPP TS 36.321 V15.3.0, entitled “SL-SCH MAC        subheader for V=‘0011’”, is reproduced as FIG. 10]        MAC PDU subheaders have the same order as the corresponding MAC        SDUs and padding.        Padding occurs at the end of the MAC PDU, except when        single-byte or two-byte padding is required. Padding may have        any value and the MAC entity shall ignore it. When padding is        performed at the end of the MAC PDU, zero or more padding bytes        are allowed.        When single-byte or two-byte padding is required, one or two MAC        PDU subheaders corresponding to padding are placed after the        SL-SCH subheader and before any other MAC PDU subheader.        A maximum of one MAC PDU can be transmitted per TB.    -   [FIG. 6.1.6-4 of 3GPP TS 36.321 V15.3.0, entitled “Example of        MAC PDU consisting of MAC header, MAC SDUs and padding”, is        reproduced as FIG. 11]

3GPP TS 36.331 V15.2.2 describes RRC procedure related to V2X sidelinkcommunication as follows:

5.10.1d Conditions for V2X Sidelink Communication Operation

When it is specified that the UE shall perform V2X sidelinkcommunication operation only if the conditions defined in this sectionare met, the UE shall perform V2X sidelink communication operation onlyif:

-   -   1> if the UE's serving cell is suitable (RRC_IDLE or        RRC_CONNECTED); and if either the selected cell on the frequency        used for V2X sidelink communication operation belongs to the        registered or equivalent PLMN as specified in TS 24.334 [69] or        the UE is out of coverage on the frequency used for V2X sidelink        communication operation as defined in TS 36.304 [4, 11.4]; or    -   1> if the UE's serving cell (for RRC_IDLE or RRC_CONNECTED)        fulfils the conditions to support V2X sidelink communication in        limited service state as specified in TS 23.285 [78, 4.4.8]; and        if either the serving cell is on the frequency used for V2X        sidelink communication operation or the UE is out of coverage on        the frequency used for V2X sidelink communication operation as        defined in TS 36.304 [4, 11.4]; or    -   1> if the UE has no serving cell (RRC_IDLE);        5.10.2 Sidelink UE Information        5.10.2.1 General    -   [FIG. 5.10.2-1 of 3GPP TS 36.331 V15.2.2, entitled “Sidelink UE        information”, is reproduced as FIG. 12]        The purpose of this procedure is to inform E-UTRAN that the UE        is interested or no longer interested to receive sidelink        communication or discovery, to receive V2X sidelink        communication, as well as to request assignment or release of        transmission resources for sidelink communication or discovery        announcements or V2X sidelink communication or sidelink        discovery gaps, to report parameters related to sidelink        discovery from system information of inter-frequency/PLMN cells        and to report the synchronization reference used by the UE for        V2X sidelink communication.        5.10.2.2 Initiation        A UE capable of sidelink communication or V2X sidelink        communication or sidelink discovery that is in RRC_CONNECTED may        initiate the procedure to indicate it is (interested in)        receiving sidelink communication or V2X sidelink communication        or sidelink discovery in several cases including upon successful        connection establishment, upon change of interest, upon change        to a PCell broadcasting SystemInformationBlockType18 or        SystemInformationBlockType19 or SystemInformationBlockType21        including sl-V2X-ConfigCommon. A UE capable of sidelink        communication or V2X sidelink communication or sidelink        discovery may initiate the procedure to request assignment of        dedicated resources for the concerned sidelink communication        transmission or discovery announcements or V2X sidelink        communication transmission or to request sidelink discovery gaps        for sidelink discovery transmission or sidelink discovery        reception and a UE capable of inter-frequency/PLMN sidelink        discovery parameter reporting may initiate the procedure to        report parameters related to sidelink discovery from system        information of inter-frequency/PLMN cells.    -   NOTE 1: A UE in RRC_IDLE that is configured to transmit sidelink        communication/V2X sidelink communication/sidelink discovery        announcements, while        SystemInformationBlockType18/SystemInformationBlockType19/SystemInformationBlockType21        including sl-V2X-ConfigCommon does not include the resources for        transmission (in normal conditions), initiates connection        establishment in accordance with 5.3.3.1a.        Upon initiating the procedure, the UE shall:        [ . . . ]    -   1> if SystemInformationBlockType21 including sl-V2X-ConfigCommon        is broadcast by the PCell:        -   2> ensure having a valid version of            SystemInformationBlockType21 for the PCell;        -   2> if configured by upper layers to receive V2X sidelink            communication on a primary frequency or on one or more            frequencies included in v2x-InterFreqInfoList, if included            in SystemInformationBlockType21 of the PCell:            -   3> if the UE did not transmit a SidelinkUEInformation                message since last entering RRC_CONNECTED state; or            -   3> if since the last time the UE transmitted a                SidelinkUEInformation message the UE connected to a                PCell not broadcasting SystemInformationBlockType21                including sl-V2X-ConfigCommon; or            -   3> if the last transmission of the SidelinkUEInformation                message did not include v2x-CommRxInterestedFreqList; or                if the frequency(ies) configured by upper layers to                receive V2X sidelink communication on has changed since                the last transmission of the SidelinkUEInformation                message:                -   4> initiate transmission of the                    SidelinkUEInformation message to indicate the V2X                    sidelink communication reception frequency(ies) of                    interest in accordance with 5.10.2.3;        -   2> else:            -   3> if the last transmission of the SidelinkUEInformation                message included v2x-CommRxInterestedFreqList:                -   4> initiate transmission of the                    SidelinkUEInformation message to indicate it is no                    longer interested in V2X sidelink communication                    reception in accordance with 5.10.2.3;        -   2> if configured by upper layers to transmit V2X sidelink            communication on a primary frequency or on one or more            frequencies included in v2x-InterFreqInfoList, if included            in SystemInformationBlockType21 of the PCell:            -   3> if the UE did not transmit a SidelinkUEInformation                message since last entering RRC_CONNECTED state; or            -   3> if since the last time the UE transmitted a                SidelinkUEInformation message the UE connected to a                PCell not broadcasting SystemInformationBlockType21                including sl-V2X-ConfigCommon; or            -   3> if the last transmission of the SidelinkUEInformation                message did not include v2x-CommTxResourceReq; or if the                information carried by the v2x-CommTxResourceReq has                changed since the last transmission of the                SidelinkUEInformation message:                -   4> initiate transmission of the                    SidelinkUEInformation message to indicate the V2X                    sidelink communication transmission resources                    required by the UE in accordance with 5.10.2.3;        -   2> else:            -   3> if the last transmission of the SidelinkUEInformation                message included v2x-CommTxResourceReq:                -   4> initiate transmission of the                    SidelinkUEInformation message to indicate it no                    longer requires V2X sidelink communication                    transmission resources in accordance with 5.10.2.3;                    5.10.2.3 Actions Related to Transmission of                    SidelinkUEInformation Message                    The UE shall set the contents of the                    SidelinkUEInformation message as follows:    -   1> if the UE initiates the procedure to indicate it is (no more)        interested to receive sidelink communication or discovery or        receive V2X sidelink communication or to request        (configuration/release) of sidelink communication or V2X        sidelink communication or sidelink discovery transmission        resources (i.e. UE includes all concerned information,        irrespective of what triggered the procedure):        [ . . . ]    -   2> if SystemInformationBlockType21 is broadcast by the PCell and        SystemInformationBlockType21 includes sl-V2X-ConfigCommon:    -   3> if configured by upper layers to receive V2X sidelink        communication:    -   4> include v2x-CommRxInterestedFreqList and set it to the        frequency(ies) for V2X sidelink communication reception;    -   3> if configured by upper layers to transmit V2X sidelink        communication:    -   4> if configured by upper layers to transmit P2X related V2X        sidelink communication:    -   5> include p2x-CommTxType set to true;    -   4> include v2x-CommTxResourceReq and set its fields as follows        for each frequency on which the UE is configured for V2X        sidelink communication transmission:    -   5> set carrierFreqCommTx to indicate the frequency for V2X        sidelink communication transmission;    -   5> set v2x-TypeTxSync to the current synchronization reference        type used on the associated carrierFreqCommTx for V2X sidelink        communication transmission;    -   5> set v2x-DestinationInfoList to include the V2X sidelink        communication transmission destination(s) for which it requests        E-UTRAN to assign dedicated resources;    -   1> else if the UE initiates the procedure to request sidelink        discovery transmission and/or reception gaps:        -   2> if the UE is configured with gapRequestsAllowedDedicated            set to true; or        -   2> if the UE is not configured with            gapRequestsAllowedDedicated and gapRequestsAllowedCommon is            included in SystemInformationBlockType19:            -   3> if the UE requires sidelink discovery gaps to monitor                the sidelink discovery announcements the UE is                configured to monitor by upper layers:                -   4> include discRxGapReq and set it to indicate, for                    each frequency that either concerns the primary                    frequency or is included in discInterFreqList on                    which the UE is configured to monitor sidelink                    discovery announcements and for which it requires                    sidelink discovery gaps to do so, the gap pattern(s)                    as well as the concerned frequency, if different                    from the primary;            -   3> if the UE requires sidelink discovery gaps to                transmit the sidelink discovery announcements the UE is                configured to transmit by upper layers:                -   4> include discTxGapReq and set it to indicate, for                    each frequency that either concerns the primary or                    is included in discInterFreqList on which the UE is                    configured to transmit sidelink discovery                    announcements and for which it requires sidelink                    discovery gaps to do so, the gap pattern(s) as well                    as the concerned frequency, if different from the                    primary;    -   1> else if the UE initiates the procedure to report the system        information parameters related to sidelink discovery of carriers        other than the primary:        -   2> include discSysInfoReportFreqList and set it to report            the system information parameter acquired from the cells on            those carriers;            The UE shall submit the SidelinkUEInformation message to            lower layers for transmission.            [ . . . ]            5.10.13 V2X Sidelink Communication Transmission            5.10.13.1 Transmission of V2X Sidelink Communication            A UE capable of V2X sidelink communication that is            configured by upper layers to transmit V2X sidelink            communication and has related data to be transmitted shall:    -   1> if the conditions for sidelink operation as defined in        5.10.1d are met:        -   2> if in coverage on the frequency used for V2X sidelink            communication as defined in TS 36.304 [4, 11.4]; or        -   2> if the frequency used to transmit V2X sidelink            communication is included in v2x-InterFreqInfoList in            RRCConnectionReconfiguration or in v2x-InterFreqInfoList            within SystemInformationBlockType21:            -   3> if the UE is in RRC_CONNECTED and uses the PCell or                the frequency included in v2x-InterFreqInfoList in                RRCConnectionReconfiguration for V2X sidelink                communication:                -   4> if the UE is configured, by the current PCell                    with commTxResources set to scheduled:                -    5> if T310 or T311 is running; and if the PCell at                    which the UE detected physical layer problems or                    radio link failure broadcasts                    SystemInformationBlockType21 including                    v2x-CommTxPoolExceptional in sl-V2X-ConfigCommon, or                    v2x-CommTxPoolExceptional is included in                    v2x-InterFreqInfoList for the concerned frequency in                    SystemInformationBlockType21 or                    RRCConnectionReconfiguration; or                -    5> if T301 is running and the cell on which the UE                    initiated connection re-establishment broadcasts                    SystemInformationBlockType21 including                    v2x-CommTxPoolExceptional in sl-V2X-ConfigCommon, or                    v2x-CommTxPoolExceptional is included in                    v2x-InterFreqInfoList for the concerned frequency in                    SystemInformationBlockType21; or                -    5> if T304 is running and the UE is configured with                    v2x-CommTxPoolExceptional included in                    mobilityControlInfoV2X in                    RRCConnectionReconfiguration or in                    v2x-InterFreqInfoList for the concerned frequency in                    RRCConnectionReconfiguration:                -    6> configure lower layers to transmit the sidelink                    control information and the corresponding data based                    on random selection using the pool of resources                    indicated by v2x-CommTxPoolExceptional as defined in                    TS 36.321 [6];                -    5> else:                -    6> configure lower layers to request E-UTRAN to                    assign transmission resources for V2X sidelink                    communication;                -   4> else if the UE is configured with                    v2x-CommTxPoolNormalDedicated or                    v2x-CommTxPoolNormal or p2x-CommTxPoolNormal in the                    entry of v2x-InterFreqInfoList for the concerned                    frequency in sl-V2X-ConfigDedicated in                    RRCConnectionReconfiguration:                -    5> if the UE is configured to transmit non-P2X                    related V2X sidelink communication and a result of                    sensing on the resources configured in                    v2x-CommTxPoolNormalDedicated or                    v2x-CommTxPoolNormal in the entry of                    v2x-InterFreqInfoList for the concerned frequency in                    RRCConnectionReconfiguration is not available in                    accordance with TS 36.213 [23]; or                -    5> if the UE is configured to transmit P2X related                    V2X sidelink communication and selects to use                    partial sensing according to 5.10.13.1a, and a                    result of partial sensing on the resources                    configured in v2x-CommTxPoolNormalDedicated or                    p2x-CommTxPoolNormal in the entry of                    v2x-InterFreqInfoList for the concerned frequency in                    RRCConnectionReconfiguration is not available in                    accordance with TS 36.213 [23]:                -    6> if v2x-CommTxPoolExceptional is included in                    mobilityControlInfoV2X in                    RRCConnectionReconfiguration (i.e., handover case);                    or                -    6> if v2x-CommTxPoolExceptional is included in the                    entry of v2x-InterFreqInfoList for the concerned                    frequency in RRCConnectionReconfiguration; or                -    6> if the PCell broadcasts                    SystemInformationBlockType21 including                    v2x-CommTxPoolExceptional in sl-V2X-ConfigCommon or                    v2x-CommTxPoolExceptional in v2x-InterFreqInfoList                    for the concerned frequency:                -    7> configure lower layers to transmit the sidelink                    control information and the corresponding data based                    on random selection using the pool of resources                    indicated by v2x-CommTxPoolExceptional as defined in                    TS 36.321 [6];                -    5> else if the UE is configured to transmit P2X                    related V2X sidelink communication:                -    6> select a resource pool according to 5.10.13.2;                -    6> perform P2X related V2X sidelink communication                    according to 5.10.13.1a;                -    5> else if the UE is configured to transmit non-P2X                    related V2X sidelink communication:                -    6> configure lower layers to transmit the sidelink                    control information and the corresponding data based                    on sensing (as defined in TS 36.321 [6] and TS                    36.213 [23]) using one of the resource pools                    indicated by v2x-commTxPoolNormalDedicated or                    v2x-CommTxPoolNormal in the entry of                    v2x-InterFreqInfoList for the concerned frequency,                    which is selected according to 5.10.13.2;            -   3> else:                -   4> if the cell chosen for V2X sidelink communication                    transmission broadcasts                    SystemInformationBlockType21:                -    5> if the UE is configured to transmit non-P2X                    related V2X sidelink communication, and if                    SystemInformationBlockType21 includes                    v2x-CommTxPoolNormalCommon or v2x-CommTxPoolNormal                    in v2x-InterFreqInfoList for the concerned frequency                    in sl-V2X-ConfigCommon and a result of sensing on                    the resources configured in                    v2x-CommTxPoolNormalCommon or v2x-CommTxPoolNormal                    in v2x-InterFreqInfoList for the concerned frequency                    is available in accordance with TS 36.213 [23]:                -    6> configure lower layers to transmit the sidelink                    control information and the corresponding data based                    on sensing (as defined in TS 36.321 [6] and TS                    36.213 [23]) using one of the resource pools                    indicated by v2x-CommTxPoolNormalCommon or                    v2x-CommTxPoolNormal in v2x-InterFreqInfoList for                    the concerned frequency, which is selected according                    to 5.10.13.2;                -    5> else if the UE is configured to transmit P2X                    related V2X sidelink communication, and if                    SystemInformationBlockType21 includes                    p2x-CommTxPoolNormalCommon or p2x-CommTxPoolNormal                    in v2x-InterFreqInfoList for the concerned frequency                    in sl-V2X-ConfigCommon, and if the UE selects to use                    random selection according to 5.10.13.1a, or selects                    to use partial sensing according to 5.10.13.1a and a                    result of partial sensing on the resources                    configured in p2x-CommTxPoolNormalCommon or                    p2x-CommTxPoolNormal in v2x-InterFreqInfoList for                    the concerned frequency is available in accordance                    with TS 36.213 [23]:                -    6> select a resource pool from                    p2x-CommTxPoolNormalCommon or p2x-CommTxPoolNormal                    in v2x-InterFreqInfoList for the concerned frequency                    according to 5.10.13.2, but ignoring zoneConfig in                    SystemInformationBlockType21;                -    6> perform P2X related V2X sidelink communication                    according to 5.10.13.1a;                -    5> else if SystemInformationBlockType21 includes                    v2x-CommTxPoolExceptional in sl-V2X-ConfigCommon or                    v2x-CommTxPoolExceptional in v2x-InterFreqInfoList                    for the concerned frequency:                -    6> from the moment the UE initiates connection                    establishment until receiving an                    RRCConnectionReconfiguration including                    sl-V2X-ConfigDedicated, or until receiving an                    RRCConnectionRelease or an RRCConnectionReject; or                -    6> if the UE is in RRC_IDLE and a result of sensing                    on the resources configured in                    v2x-CommTxPoolNormalCommon or v2x-CommTxPoolNormal                    in v2x-InterFreqInfoList for the concerned frequency                    in Systeminformationblocktype21 is not available in                    accordance with TS 36.213 [23]; or                -    6> if the UE is in RRC_IDLE and UE selects to use                    partial sensing according to 5.10.13.1a and a result                    of partial sensing on the resources configured in                    p2x-CommTxPoolNormalCommon or p2x-CommTxPoolNormal                    in v2x-InterFreqInfoList for the concerned frequency                    in Systeminformationblocktype21 is not available in                    accordance with TS 36.213 [23]:                -    7> configure lower layers to transmit the sidelink                    control information and the corresponding data based                    on random selection (as defined in TS 36.321 [6])                    using the pool of resources indicated in                    v2x-CommTxPoolExceptional;        -   2> else:            -   3> configure lower layers to transmit the sidelink                control information and the corresponding data based on                sensing (as defined in TS 36.321 [6] and TS 36.213 [23])                using one of the resource pools indicated by                v2x-CommTxPoolList in SL-V2X-Preconfiguration in case of                non-P2X related V2X sidelink communication, which is                selected according to 5.10.13.2, or using one of the                resource pools indicated by p2x-CommTxPoolList in                SL-V2X-Preconfiguration in case of P2X related V2X                sidelink communication, which is selected according to                5.10.13.2, and in accordance with the timing of the                selected reference as defined in 5.10.8;                The UE capable of non-P2X related V2X sidelink                communication that is configured by upper layers to                transmit V2X sidelink communication shall perform                sensing on all pools of resources which may be used for                transmission of the sidelink control information and the                corresponding data. The pools of resources are indicated                by SL-V2X-Preconfiguration, v2x-CommTxPoolNormalCommon,                v2x-CommTxPoolNormalDedicated in sl-V2X-ConfigDedicated,                or v2x-CommTxPoolNormal in v2x-InterFreqInfoList for the                concerned frequency, as configured above.    -   NOTE 1: If there are multiple frequencies for which normal or        exceptional pools are configured, it is up to UE implementation        which frequency is selected for V2X sidelink communication        transmission.        5.10.13.2 V2X Sidelink Communication Transmission Pool Selection        For a frequency used for V2X sidelink communication, if        zoneConfig is not ignored as specified in 5.10.13.1, the UE        configured by upper layers for V2X sidelink communication shall        only use the pool which corresponds to geographical coordinates        of the UE, if zoneConfig is included in        SystemInformationBlockType21 of the serving cell        (RRC_IDLE)/PCell (RRC_CONNECTED) or in        RRCConnectionReconfiguration for the concerned frequency, and        the UE is configured to use resource pools provided by RRC        signalling for the concerned frequency; or if zoneConfig is        included in SL-V2X-Preconfiguration for the concerned frequency,        and the UE is configured to use resource pools in        SL-V2X-Preconfiguration for the frequency, according to        5.10.13.1. The UE shall only use the pool which is associated        with the synchronization reference source selected in accordance        with 5.10.8.2.    -   1> if the UE is configured to transmit on        p2x-CommTxPoolNormalCommon or on p2x-CommTxPoolNormal in        v2x-InterFreqInfoList in SystemInformationBlockType21 according        to 5.10.13.1; or    -   1> if the UE is configured to transmit on p2x-CommTxPoolList-r14        in SL-V2X-Preconfiguration according to 5.10.13.1; or    -   1> if zoneConfig is not included in SystemInformationBlockType21        and the UE is configured to transmit on        v2x-CommTxPoolNormalCommon or v2x-CommTxPoolNormalDedicated; or    -   1> if zoneConfig is included in SystemInformationBlockType21 and        the UE is configured to transmit on        v2x-CommTxPoolNormalDedicated for P2X related V2X sidelink        communication and zoneID is not included in        v2x-CommTxPoolNormalDedicated; or    -   1> if zoneConfig is not included in the entry of        v2x-InterFreqInfoList for the concerned frequency and the UE is        configured to transmit on v2x-CommTxPoolNormal in        v2x-InterFreqInfoList or p2x-CommTxPoolNormal in        v2x-InterFreqInfoList in RRCConnectionReconfiguration; or    -   1> if zoneConfig is not included in SL-V2X-Preconfiguration for        the concerned frequency and the UE is configured to transmit on        v2x-CommTxPoolList in SL-V2X-Preconfiguration for the concerned        frequency:        -   2> select the first pool associated with the synchronization            reference source selected in accordance with 5.10.8.2;    -   1> if zoneConfig is included in SystemInformationBlockType21 and        the UE is configured to transmit on v2x-CommTxPoolNormalCommon        or v2x-CommTxPoolNormalDedicated for non-P2X related V2X        sidelink communication; or    -   1> if zoneConfig is included in SystemInformationBlockType21 and        the UE is configured to transmit on        v2x-CommTxPoolNormalDedicated for P2X related V2X sidelink        communication and zoneID is included in        v2x-CommTxPoolNormalDedicated; or    -   1> if zoneConfig is included in the entry of        v2x-InterFreqInfoList for the concerned frequency and the UE is        configured to transmit on v2x-CommTxPoolNormal in        v2x-InterFreqInfoList or p2x-CommTxPoolNormal in        v2x-InterFreqInfoList in RRCConnectionReconfiguration; or    -   1> if zoneConfig is included in SL-V2X-Preconfiguration for the        concerned frequency and the UE is configured to transmit on        v2x-CommTxPoolList in SL-V2X-Preconfiguration for the concerned        frequency:        -   2> select the pool configured with zoneID equal to the zone            identity determined below and associated with the            synchronization reference source selected in accordance with            5.10.8.2;            The UE shall determine an identity of the zone (i.e.            Zone_id) in which it is located using the following            formulae, if zoneConfig is included in            SystemInformationBlockType21 or in SL-V2X-Preconfiguration:            x ₁=Floor(x/L)Mod Nx;            y ₁=Floor(y/W)Mod Ny;            Zone_id=y ₁ *Nx+x ₁.            The parameters in the formulae are defined as follows:    -   L is the value of zoneLength included in zoneConfig in        SystemInformationBlockType21 or in SL-V2X-Preconfiguration;    -   W is the value of zoneWidth included in zoneConfig in        SystemInformationBlockType21 or in SL-V2X-Preconfiguration;    -   Nx is the value of zoneIdLongiMod included in zoneConfig in        SystemInformationBlockType21 or in SL-V2X-Preconfiguration;    -   Ny is the value of zoneIdLatiMod included in zoneConfig in        SystemInformationBlockType21 or in SL-V2X-Preconfiguration;    -   x is the geodesic distance in longitude between UE's current        location and geographical coordinates (0, 0) according to WGS84        model [80] and it is expressed in meters;    -   y is the geodesic distance in latitude between UE's current        location and geographical coordinates (0, 0) according to WGS84        model [80] and it is expressed in meters.        The UE shall select a pool of resources which includes a zoneID        equals to the Zone_id calculated according to above mentioned        formulae and indicated by v2x-CommTxPoolNormalDedicated,        v2x-CommTxPoolNormalCommon, v2x-CommTxPoolNormal in        v2x-InterFreqInfoList or p2x-CommTxPoolNormal in        v2x-InterFreqInfoList in RRCConnectionReconfiguration, or        v2x-CommTxPoolList according to 5.10.13.1.    -   NOTE 1: The UE uses its latest geographical coordinates to        perform resource pool selection.    -   NOTE 2: If geographical coordinates are not available and zone        specific TX resource pools are configured for the concerned        frequency, it is up to UE implementation which resource pool is        selected for V2X sidelink communication transmission.

In the RAN1#94 Chairman's Note, the agreements of NR V2X are describedas follows:

Agreements:

-   1 At least two sidelink resource allocation modes are defined for    NR-V2X sidelink communication    -   Mode 1: Base station schedules sidelink resource(s) to be used        by UE for sidelink transmission(s)    -   Mode 2: UE determines (i.e. base station does not schedule)        sidelink transmission resource(s) within sidelink resources        configured by base station/network or pre-configured sidelink        resources        Notes:    -   eNB control of NR sidelink and gNB control of LTE sidelink        resources will be separately considered in corresponding agenda        items.    -   Mode-2 definition covers potential sidelink radio-layer        functionality or resource allocation sub-modes (subject to        further refinement including merging of some or all of them)        where    -   a) UE autonomously selects sidelink resource for transmission    -   b) UE assists sidelink resource selection for other UE(s)    -   c) UE is configured with NR configured grant (type-1 like) for        sidelink transmission    -   d) UE schedules sidelink transmissions of other UEs-   2 RAN1 to continue study details of resource allocation modes for    NR-V2X sidelink communication

One or multiple of following terminologies may be used hereafter:

-   -   BS: A network central unit or a network node in NR which is used        to control one or multiple TRPs which are associated with one or        multiple cells. Communication between BS and TRP(s) is via        fronthaul. BS could also be referred to as central unit (CU),        eNB, gNB, or NodeB.    -   TRP: A transmission and reception point provides network        coverage and directly communicates with UEs. TRP could also be        referred to as distributed unit (DU) or network node.    -   Cell: A cell is composed of one or multiple associated TRPs,        i.e. coverage of the cell is composed of coverage of all        associated TRP(s). One cell is controlled by one BS. Cell could        also be referred to as TRP group (TRPG).

One or multiple of following assumptions for network side may be usedhereafter:

-   -   Downlink timing of TRPs in the same cell are synchronized.    -   RRC layer of network side is in BS.

One or multiple of following assumptions for UE side may be usedhereafter:

-   -   There are at least two UE (RRC) states: connected state (or        called active state) and non-connected state (or called inactive        state or idle state). Inactive state may be an additional state        or belong to connected state or non-connected state.

In LTE V2X (Vehicle-to-Everything), a Tx profile is used by the upperlayers to select between R14 or R15 transmission format in AS (AccessStratum) layer. Given mapping between V2X service identifiers and Txprofiles, the upper layer determines the Tx profile to use fortransmitting a packet based on the V2X service identifier (e.g. PSID(Provider Service Identifier) or ITS-AID (ITS Application Identifier) ofthe V2X application) and then provides the Tx profile to the AS with thepacket. Besides, since each service is associated with a specificdestination layer-2 ID for one-to-many communication, the Tx profile maybe provided with the destination layer-2 ID associated with the V2Xservice to AS layer. And, AS layer may then determine transmissionformat for a packet just based on the destination layer-2 ID associatedwith the packet. The concept is shown in FIG. 13, which illustrates anexemplary embodiment for transmission profile applied on one-to-manycommunication. In case of network scheduled operation mode, eNB canschedule the UE based on SL BSR which includes the destination indexassociated with data in the buffer.

On the other hand, in scope of NR V2X study, there is also a need tostudy one-to-one communication in addition to one-to-many communication.In LTE V2X, a UE will be self-allocated with an UE ID for representingitself. The UE will use the UE ID as source layer-2 ID in anyone-to-many communication for other UEs to differentiate differentcommunications. Regarding the one-to-one communication (i.e. Unicast),it is straightforward to reuse the UE ID as a source layer-2 ID inunicast for other UEs to differentiate different communications. And adestination of a one-to-one communication will be another UE IDbelonging to another UE. The assumption is shown in FIG. 14.

Based on the assumption, since the UE ID self-allocated within each UEis just for identifying itself and thus destination ID of a UE is notintrinsically mapped to a specific V2X service, the one-to-onecommunication of different services cannot be differentiated bydestination ID of a UE. As a consequence, one-to-one communication ofdifferent services could not be served by different AS parameters (e.g.MCS, transmission format, SCS, TBS) as V2X in LTE. Similarly, theone-to-one communication of different services also cannot be served bydifferent RATs. In case of network scheduled operation mode, eNB willnot be able to schedule the UE based on SL BSR because the associationbetween the destination index or layer-2 ID and Tx profile does notexist.

Considering supporting different RATs case, some possible solutions forRAT differentiation are discussed below.

Solution 1: Allocate a UE with Multiple UE IDs for One-to-OneCommunication. And Different UE IDs Will be Associated with DifferentRATs.

In this method, a UE could be allocated with different UE IDs fordifferent RATs. The UE IDs will be used as source layer-2 IDs forperforming sidelink transmissions for corresponding services. In oneembodiment, a UE could be based on the different UE IDs for receivingdata from different RATs. The different UE IDs may be allocated forone-to-one communications. The UE IDs could be self-allocated.Alternatively, the UE IDs could be network allocated.

The association between the UE IDs and RATs could be determined based ontransmission profile(s). For example, a service is associated with atransmission profile. And the transmission profile could indicateappropriate RAT for one-to-one communication of the service. The UEcould link the one-to-one communication of the service to a UE ID forone-to-one communication in corresponding RAT.

For mode 1, the UE may need to separately report resource demands ofdifferent RATs. One possible way is to report resource demand in perdestination way in a MAC CE. Another possible way is to report resourcedemand in per source-destination pair way in a MAC CE. Another possibleway is to report resource demand in different MAC CEs for differentRATs. The different MAC CEs will be identified by different MACsubheaders. Another possible way is to include a new field forindicating RAT difference of each buffer size.

For mode 2, the UE could select resource from which RAT for transmittinga data of a service based on a transmission profile associated with theservice or the UE ID (source layer-2 ID) associated with the service.

In one embodiment, the association could be established by including theUE ID (source layer-2 ID and/or destination layer-2 ID) in atransmission profile for a service. Alternatively, the association couldbe established by including RAT information in a transmission profilefor a service. The UE IDs for one-to-one sidelink communication indifferent RATs could be self-allocated and/or allocated by a network(e.g. V2X server, BS, Core network, V2X control function, V2Xapplication).

In one embodiment, the UE could report transmission profile informationand/or the association to the network (e.g. base station). The UE couldreport at least one or multiple information listed below:

1. V2X service identity

2. Transmission profile identity

3. QoS (Quality of Service) information (e.g. 5QI value)

4. RAT (Radio Access Technology) indication

5. Source layer-2 ID

6. Destination layer-2 ID

In one embodiment, the above information could be reported through a RRC(Radio Resource Control) message.

In one embodiment, the UE could include a new field in Sidelink BSR(Buffer Status Report) for indicating transmission profile of thedestination or the source-destination pair. Based on the information,the base station could schedule correct sidelink resource to the UE forthe destination or the source-destination pair. The new field couldindicate one or multiple information listed below:

1. Transmission profile

2. Subcarrier spacing

3. Bandwidth part

4. Carrier

5. Transmission power

6. MCS

7. TB (Transport Block) size

8. RAT

9. Whether applying HARQ (Hybrid Automatic Repeat Request) feedbackmechanism

10. Cast type

Solution 2: Define One-to-One V2X Sidelink Communication can Only Happenin NR

In this solution, the RAT selection could be predefined. The one-to-oneV2X sidelink communication always performs based on resource in NR. Whena UE initiates an one-to-one V2X sidelink communication, the UE coulddirectly request or select resource in NR. In one embodiment, the UEcould send a RRC message to a BS for indicating one-to-one V2X sidelinkcommunication initiation, if the UE is in RRC CONNECTED state. The UEcould send a BSR for indicating buffer sizes for one-to-one V2X sidelinkcommunications for requesting resource from NR, if the UE is configuredto perform model in NR.

In one embodiment, the resources in different RATs could be provided bythe same base station. The resources in different RATs could be providedby the PCell (Primary Cell). The resources in different RATs could alsobe provided in different scheduling modes.

Solution 3: Provide Service Information for Network to Control

In LTE V2X, there could be a mapping between V2X services (e.g. PSID orITS-AID of the V2X application) and Tx profiles and each V2X service isassociated with a Destination Layer-2 ID. With the previous information,eNB can know the required Tx profile for scheduling the UE based on thedestination index included in SL (Sidelink) BSR for one-to-many directcommunication.

It is possible the above concepts may be reused for one-to-one directcommunication in NR, e.g. there is also a mapping between V2X services(e.g. PSID or ITS-AID of the V2X applications) and Tx profiles and SLBSR is also formatted according to destination indexes for one-to-onedirect communications. Then, what is lacking would be the associationbetween the V2X service and the Destination Layer-2 ID/destination indexfor the concerned one-to-one direct communication. Therefore, theconcept of this approach could be the UE provides information for gNB toassociate the V2X service with the Destination Layer-2 ID or destinationindex for the concerned one-to-one direct communication.

In LTE, SidelinkUEInformation may include an IE v2x-DestinationInfoList.If the IE is also reused for the UE to request resources for NRone-to-one direct communications, V2X services corresponding to thev2x-DestinationInfoList could be included in SidelinkUEInformation forgNB to associate each V2X service with a Destination Layer-2ID/destination index. An example is shown in FIG. 16. Alternatively,other dedicated signaling may be used to provide information forassociating the V2X service with the Destination ID for the one-to-onedirect communication.

In the example, the UE could send a list of destinations to a basestation through a RRC message (e.g. SidelinkUEInformation). In oneembodiment, different services could be associated with differentdestinations or different UEs. However, it is also possible thatdifferent services may be associated with the same destinations or sameUEs (i.e. a one-to-one communication between the same source-destinationpair may support multiple V2X services). In this situation, thev2x-DestinationInfoList may include multiple entries of the samedestination ID, and thus each destination index (corresponding to onedestination ID in the list) in the SL BSR can be associated with one V2Xservice. As a result, eNB can then determine the required Tx profile orRAT for scheduling the UE based on the destination index included in SLBSR for the one-to-one direct communication.

In one embodiment, the UE may know the association between destinationand service based on configuration (e.g. NAS configuration, transmissionprofile). Since the base station cannot know resource type demand (e.g.resource in which RAT) of a destination, the UE may need to provideassistance information to inform the base station. In one example, theassistance information may include a V2X service information list. Thelist of V2X service information could be linked to the destination list(e.g. by one-to-one mapping or one-to-many mapping). The V2X serviceinformation may include one or multiple information listed below:

1. V2X service identity

2. Transmission profile identity

3. QoS information (e.g. 5QI value)

4. RAT indication

5. Service flow ID

In one embodiment, a UE could send a BSR to report different buffersizes for different destinations. And, the BSR may include a field forindicating resource demand of the corresponding buffer size. The fieldmay indicate one or multiple information listed below:

1. Transmission profile

2. Subcarrier spacing

3. Bandwidth part

4. Carrier

5. Transmission power

6. MCS

7. TB size

8. RAT

9. Whether applying HARQ feedback mechanism

10. Cast type

Considering possible different AS parameters case, it would bebeneficial to support service discrimination on resource allocation ofone-to-one communication. And the following possible methods areproposed for achieving the concept.

Method 1. Allocating a UE with Multiple UE IDs as Different Source IDsfor Different Services (for One-to-One Communication)

In this method, a UE could be allocated with different UE IDs fordifferent services. The UE IDs could be used as source layer-2 IDs forperforming sidelink transmissions for corresponding services. In oneembodiment, a UE could be based on the different UE IDs for receivingdata for the different services. The different UE IDs could be allocatedfor one-to-one communications. The UE IDs could be self-allocated.Alternatively, the UE IDs could be network allocated.

For how UE determine transmission parameters for a service, atransmission profile could be associated with one or multiple the UEIDs. And the UE could determine transmission parameters of a sidelinktransmission based on transmission profile associated with a sourcelayer-2 ID of the sidelink transmission.

For example, UE A will be allocated with UE ID A1, UE ID A2, and UE IDA3. UE ID A1 is associated with service1 and transmission profile 1. UEID A2 is associated with service2 and transmission profile 1. UE ID A3is associated with service3 and transmission profile 2. An example isshown in FIG. 15.

For mode 1, UE A may need to separately report resource demands ofdifferent transmission profiles. One possible way is to report resourcedemand in per destination way. Since UE ID used in one-to-onecommunication could be associated with service, the destination ID couldalso be associated with a specific service. Another possible way is toreport resource demand in per source-destination pair way.

For mode 2, UE A could select resource based on a transmission profile,which is determined based on association between transmission profileand service. Specifically, UE A could select resource and/ortransmission parameters based on transmission profile 1 if the UE A isgoing to transmit data for service 1 or service 2. And UE A could selectresource and/or transmission parameters based on transmission profile 2if UE A is going to transmit data for service 1 or service 2.

In one embodiment, the association could be established by including theUE ID (e.g. source layer-2 ID and/or destination layer-2 ID) in atransmission profile. Alternatively, the association could beestablished by associating both the UE ID and a transmission profile tosame V2X service identity. Alternatively, the association could beestablished by associating both the UE ID and a transmission profile tosame QoS flow or service flow.

In one embodiment, the UE could report transmission profile informationand/or the association to the network (e.g. base station). The UE mayreport the association by transmitting a list of destinations andtransmission profile related information to the network. Thetransmission profile related information could be one or multipleinformation listed below:

1. Transmission profile ID

2. Subcarrier spacing (associated with transmission profile)

3. Bandwidth part (associated with transmission profile)

4. Carrier (associated with transmission profile)

5. Transmission power (associated with transmission profile)

6. MCS

7. TB size

8. RAT

9. Whether applying HARQ feedback mechanism

10. Cast type

11. V2X service identity

12. QoS information (e.g. 5QI value)

13. Service Flow ID

The transmission profile related information and the destinations couldbe one-to-one mapping or one-to-many mapping.

In one embodiment, the UE could include a new field in Sidelink BSR forindicating transmission profile of the destination or thesource-destination pair. Based on the information, the base stationcould schedule correct sidelink resource to the UE for the destinationor the source-destination pair. Additionally, the UE may need to sendtransmission profile information to the base station (through RRCmessage). The transmission profile information or the new field couldindicate one or multiple characteristics listed below:

1. Transmission profile

2. Subcarrier spacing (associated with transmission profile or channel)

3. Bandwidth part (associated with transmission profile or channel)

4. Carrier (associated with transmission profile or channel)

5. Transmission power (associated with transmission profile or channel)

6. MCS

7. TB size

8. RAT

9. Whether applying HARQ feedback mechanism

10. Cast type

Method 2. Allocating Transmission Profile to One or Multiple Channelswithin a Scope of a Source-Destination Pair

In this method, a transmission profile could be associated with one ormultiple channel(s) belonging to a source-destination pair. In oneembodiment, the channel could be a sidelink logical channel, a(sidelink) radio bearer, a QoS flow, or a service flow.

Moreover, in one embodiment, the logical channel prioritizationprocedure could avoid MAC SDUs, from channels associated with differenttransmission profiles, being multiplexed within a transport block.Alternatively, the logical channel prioritization procedure could alsoallow MAC SDUs, from channels associated with different transmissionprofiles, being multiplexed within a transport block, if thosetransmission profiles shares at least one set of transmissionparameters.

In one embodiment, the association could be established by including anID of the channel in a transmission profile, by including source layer-2ID in the transmission profile, or by including destination layer-2 IDin the transmission profile.

For mode 1, the UE may need to separately report resource demands ofdifferent transmission profiles. Considering the association, the UE mayneed to report buffer status of a destination or a source-destinationpair separately based on transmission profile(s). In one embodiment, thebuffer status of a destination or a source-destination pair could bereported based on one or multiple characteristics listed below:

1. Transmission profile

2. Subcarrier spacing (associated with transmission profile or channel)

3. Bandwidth part (associated with transmission profile or channel)

4. Carrier (associated with transmission profile or channel)

5. Transmission power (associated with transmission profile or channel)

6. TB size

7. MCS

8. Whether applying HARQ feedback mechanism

9. RAT

10. Cast type

In one embodiment, a new field in sidelink BSR could be introduced forindicating the characteristics of a buffer size field. Alternatively,the UE could report the association between transmission profile(s) andchannel(s) to a base station. And the UE could rely on the base stationto configure channels with a proper LCG for BSR reporting.

For mode 2, the UE could select resource based on a transmissionprofile, which is determined based on association between transmissionprofile and service. Specifically, the UE could select resource and/ortransmission parameters based on a transmission profile if the UE isgoing to transmit data belonging to channel associated with thetransmission profile.

Method 3. Network Controls Transmission Parameters of V2X Service

In this method, when a RRC CONNECTED UE initiates one-to-onecommunication for a V2X service, the UE could provide information of theV2X service to a base station. The base station could provide AS layerconfigurations to the UE based on information of the V2X service.

In one embodiment, when a RRC IDLE UE or a RRC INACTIVE UE initiatesone-to-one communication for a V2X service, the UE could apply AS layerconfigurations based on system information from a base station. Thesystem information could provide a mapping between information of theV2X service and AS layer configuration. In one embodiment, the systeminformation could provide AS layer configuration.

The information of the V2X service could be one or multiple candidateslisted below:

1. QoS information of the V2X service (e.g. 5GI)

2. The V2X service identifier (e.g. PSID)

3. Service flow ID

4. UE ID (e.g. source layer-2 ID, application ID, destination layer-2ID, etc.)

The AS layer configuration includes one or multiple parameters listedbelow:

1. SDAP configuration

2. Logical channel configuration

3. RLC mode

4. PDCP duplication

5. Subcarrier spacing

6. Bandwidth part

7. Cell limitation

8. Grant-free

9. Carrier

10. Transmission power related configuration (e.g. maximum Tx power,power adjusting scale)

11. Whether applying HARQ feedback mechanism

12. RAT

13. Cast type

Regardless of any methods mentioned above, the transmission profile canindicate one or multiple AS layer transmission parameters. In oneembodiment, the transmission profile could indicate one or multipleinformation listed below:

1. RAT

2. MCS

3. Subcarrier spacing

4. Carriers

5. Bandwidth parts

6. Transmission formats

7. Transmission power limitations

8. Transmission ranges.

Furthermore, the transmission profile could indicate HARQ adaptation,corresponding MCS, corresponding (maximum or minimum) TB size, and/ortransmission mode (e.g. network scheduling mode, autonomous resourceselection mode).

The new field in the BSR could be included in per LCG (Logical ChannelGroup) of a destination way, per buffer size way, per destination(index) way, or per source-destination way. Alternatively, the new fieldin the BSR could be included in per buffer size way, per MAC-subheaderway, or per MAC CE way.

The allocation discussed above could be self-allocated. Alternatively,the allocation mentioned above could be network allocated (e.g. V2Xcontrol function, V2X application server, base station, core network).

FIG. 17 is a flow chart 1700 according to one exemplary embodiment fromthe perspective of a UE for the UE to request sidelink resources for anone-to-one V2X sidelink communication, wherein the UE supports both LTERAT and NR RAT. In step 1705, the UE initiates a one-to-one V2X sidelinkcommunication. In step 1710, the UE transmits a RRC message to a networknode to request sidelink resources from NR RAT for the one-to-one V2Xsidelink communication, and does not transmit any RRC message to thenetwork node to request sidelink resources from LTE RAT for theone-to-one V2X sidelink communication.

In one embodiment, the network node could be a base station (e.g. gNB).The RRC message could be a SidelinkUEInformation. The UE may not beallowed to transmit any RRC message to the network node to requestsidelink resources from LTE RAT for the one-to-one V2X sidelinkcommunication.

In one embodiment, the UE could transmit a BSR (Buffer Status Report)for indicating buffer sizes for the one-to-one V2X sidelinkcommunications for requesting sidelink resources from NR RAT. The UEcould be in RRC_CONNECTED state.

Referring back to FIGS. 3 and 4, in one exemplary embodiment of a UE forthe UE to request sidelink resources for an one-to-one V2X sidelinkcommunication, the device 300 includes a program code 312 stored in thememory 310. The CPU 308 could execute program code 312 to enable the UE(i) to initiate a one-to-one V2X sidelink communication, and (ii) totransmit a RRC message to a network node to request sidelink resourcesfrom NR RAT for the one-to-one V2X sidelink communication and, nottransmit any RRC message to the network node to request sidelinkresources from LTE RAT for the one-to-one V2X sidelink communication.Furthermore, the CPU 308 can execute the program code 312 to perform allof the above-described actions and steps or others described herein.

FIG. 18 is a flow chart 1800 according to one exemplary embodiment fromthe perspective of a UE for the UE to select sidelink resources for anone-to-one V2X sidelink communication, wherein the UE supports both LTERAT and NR (New Radio) RAT. In step 1805, the UE initiates a one-to-oneV2X sidelink communication. In step 1810, the UE selects sidelinkresources from NR RAT for the one-to-one V2X sidelink communication anddoes not select any sidelink resources from LTE RAT for the one-to-oneV2X sidelink communication.

In one embodiment, the UE may not be allowed to select any sidelinkresources from LTE RAT for the one-to-one V2X sidelink communication.

Referring back to FIGS. 3 and 4, in one exemplary embodiment of a UE forthe UE to request sidelink resources for an one-to-one V2X sidelinkcommunication, the device 300 includes a program code 312 stored in thememory 310. The CPU 308 could execute program code 312 to enable the UE(i) to initiate a one-to-one V2X sidelink communication, and (ii) toselect, sidelink resources from NR RAT for the one-to-one V2X sidelinkcommunication, and not select any sidelink resources from LTE RAT forthe one-to-one V2X sidelink communication. Furthermore, the CPU 308 canexecute the program code 312 to perform all of the above-describedactions and steps or others described herein.

Various aspects of the disclosure have been described above. It shouldbe apparent that the teachings herein could be embodied in a widevariety of forms and that any specific structure, function, or bothbeing disclosed herein is merely representative. Based on the teachingsherein one skilled in the art should appreciate that an aspect disclosedherein could be implemented independently of any other aspects and thattwo or more of these aspects could be combined in various ways. Forexample, an apparatus could be implemented or a method could bepracticed using any number of the aspects set forth herein. In addition,such an apparatus could be implemented or such a method could bepracticed using other structure, functionality, or structure andfunctionality in addition to or other than one or more of the aspectsset forth herein. As an example of some of the above concepts, in someaspects concurrent channels could be established based on pulserepetition frequencies. In some aspects concurrent channels could beestablished based on pulse position or offsets. In some aspectsconcurrent channels could be established based on time hoppingsequences. In some aspects concurrent channels could be establishedbased on pulse repetition frequencies, pulse positions or offsets, andtime hopping sequences.

Those of skill in the art would understand that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

Those of skill would further appreciate that the various illustrativelogical blocks, modules, processors, means, circuits, and algorithmsteps described in connection with the aspects disclosed herein may beimplemented as electronic hardware (e.g., a digital implementation, ananalog implementation, or a combination of the two, which may bedesigned using source coding or some other technique), various forms ofprogram or design code incorporating instructions (which may be referredto herein, for convenience, as “software” or a “software module”), orcombinations of both. To clearly illustrate this interchangeability ofhardware and software, various illustrative components, blocks, modules,circuits, and steps have been described above generally in terms oftheir functionality. Whether such functionality is implemented ashardware or software depends upon the particular application and designconstraints imposed on the overall system. Skilled artisans mayimplement the described functionality in varying ways for eachparticular application, but such implementation decisions should not beinterpreted as causing a departure from the scope of the presentdisclosure.

In addition, the various illustrative logical blocks, modules, andcircuits described in connection with the aspects disclosed herein maybe implemented within or performed by an integrated circuit (“IC”), anaccess terminal, or an access point. The IC may comprise a generalpurpose processor, a digital signal processor (DSP), an applicationspecific integrated circuit (ASIC), a field programmable gate array(FPGA) or other programmable logic device, discrete gate or transistorlogic, discrete hardware components, electrical components, opticalcomponents, mechanical components, or any combination thereof designedto perform the functions described herein, and may execute codes orinstructions that reside within the IC, outside of the IC, or both. Ageneral purpose processor may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

It is understood that any specific order or hierarchy of steps in anydisclosed process is an example of a sample approach. Based upon designpreferences, it is understood that the specific order or hierarchy ofsteps in the processes may be rearranged while remaining within thescope of the present disclosure. The accompanying method claims presentelements of the various steps in a sample order, and are not meant to belimited to the specific order or hierarchy presented.

The steps of a method or algorithm described in connection with theaspects disclosed herein may be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module (e.g., including executable instructions and relateddata) and other data may reside in a data memory such as RAM memory,flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a harddisk, a removable disk, a CD-ROM, or any other form of computer-readablestorage medium known in the art. A sample storage medium may be coupledto a machine such as, for example, a computer/processor (which may bereferred to herein, for convenience, as a “processor”) such theprocessor can read information (e.g., code) from and write informationto the storage medium. A sample storage medium may be integral to theprocessor. The processor and the storage medium may reside in an ASIC.The ASIC may reside in user equipment. In the alternative, the processorand the storage medium may reside as discrete components in userequipment. Moreover, in some aspects any suitable computer-programproduct may comprise a computer-readable medium comprising codesrelating to one or more of the aspects of the disclosure. In someaspects a computer program product may comprise packaging materials.

While the invention has been described in connection with variousaspects, it will be understood that the invention is capable of furthermodifications. This application is intended to cover any variations,uses or adaptation of the invention following, in general, theprinciples of the invention, and including such departures from thepresent disclosure as come within the known and customary practicewithin the art to which the invention pertains.

The invention claimed is:
 1. A method for a UE (User Equipment) torequest sidelink resources for a one-to-one V2X (Vehicle-to-Everything)sidelink communication, wherein the UE supports both LTE (Long TermEvolution) RAT (Radio Access Technology) and NR (New Radio) RAT,comprising: initiating the one-to-one V2X sidelink communication;transmitting a RRC (Radio Resource Control) message to a network node torequest sidelink resources from NR RAT for the one-to-one V2X sidelinkcommunication, wherein the RRC message includes information of V2Xservice; not transmitting any RRC message to the network node to requestsidelink resources from LTE RAT for the one-to-one V2X sidelinkcommunication; and receiving an AS (Access Stratum) layer configurationfrom the network node, wherein the AS layer configuration includesinformation of Cast Type.
 2. The method of claim 1, wherein the networknode is a base station (or gNB).
 3. The method of claim 1, wherein theRRC message is a SidelinkUEInformation.
 4. The method of claim 1,wherein the UE is not allowed to transmit any RRC message to the networknode to request sidelink resources from LTE RAT for the one-to-one V2Xsidelink communication.
 5. The method of claim 1, further comprising:transmitting a BSR (Buffer Status Report) for indicating buffer sizesfor the one-to-one V2X sidelink communications for requesting sidelinkresources from NR RAT.
 6. The method of claim 1, wherein the UE is inRRC_CONNECTED state.
 7. A UE (User Equipment), comprising: a controlcircuit; a processor installed in the control circuit; and a memoryinstalled in the control circuit and operatively coupled to theprocessor; wherein the processor is configured to execute a program codestored in the memory to: initiate a one-to-one V2X(Vehicle-to-Everything) sidelink communication; transmit a RRC (RadioResource Control) message to a network node to request sidelinkresources from NR (New Radio) RAT (Radio Access Technology) for theone-to-one V2X sidelink communication, wherein the RRC message includesinformation of V2X service; not transmit any RRC message to the networknode to request sidelink resources from LTE (Long Term Evolution) RATfor the one-to-one V2X sidelink communication; and receive an AS (AccessStratum) layer configuration from the network node, wherein the AS layerconfiguration includes information of Cast Type.
 8. The UE of claim 7,wherein the network node is a base station (or gNB).
 9. The UE of claim7, wherein the RRC message is a SidelinkUEInformation.
 10. The UE ofclaim 7, wherein the UE is not allowed to transmit any RRC message tothe network node to request sidelink resources from LTE RAT for theone-to-one V2X sidelink communication.
 11. The UE of claim 7, furthercomprising: transmitting a BSR (Buffer Status Report) for indicatingbuffer sizes for the one-to-one V2X sidelink communications forrequesting sidelink resources from NR RAT.
 12. The UE of claim 7,wherein the UE is in RRC_CONNECTED state.
 13. The method of claim 1,wherein the information of Cast Type is Unicast.
 14. The method of claim1, wherein the information of V2X service includes at least QoSinformation of the V2X service and/or Destination Layer-2 ID.
 15. Themethod of claim 7, wherein the information of Cast Type is Unicast. 16.The method of claim 7, wherein the information of V2X service includesat least QoS information of the V2X service and/or Destination Layer-2ID.